One step at a time. Laura Muir knew if she wanted to stride forth into the arena on Friday night in Tokyo and engage in a gladiatorial duel for gold and glory, then the right to lay it all on the line had to be earned.

First leg of her mission accomplished. The Scot swept into the second Olympic final of her career with the perk of holding a little bit in reserve by coming second in her 1500 metres semi-final in 4 mins 0.73 secs. Behind her was Dutch dynamo Sifan Hassan, with the 5000m champion still apparently fresh and determined to accomplice an unprecedented title treble here.

Their Kenyan rival Faith Kipyegon set out her own stall by winning her semi in an intimidating 3:56.80. Yet Muir, seven in Rio in 2016, will now gear up for one final fling that will likely define her legacy and career.

“Everybody always talks about the final but you’ve got to get there first,” the 28-year-old said. “And to make an Olympic final is still a really big achievement and I’m very happy that I’m there now and I can now focus on that final.

“I saw we were clear at the end so I just eased down a bit. But I knew the first semi-final was quite quick so I knew the fastest loser spots were going to be quite tough.

“There were a lot of girls still quite close behind me I just wanted to make sure I didn’t get pipped on the line or anything. Everything is going as best as it could have done.”

Barely 24 hours after Karsten Warholm’s victory in the men’s 400m hurdles final headlined one of the greatest races in history, their female counterparts combined to wrestle the front page for themselves.

Sydney McLaughlin usurped Rio 2016 gold medallist Dalilah Muhammed as world record holder at the USA’s cutthroat Olympic trials. Trailing her compatriot off the penultimate hurdle, the 21-year-old gazelle extended her stride and began to gallop, the duel as the line approached pushing McLaughlin toward unchartered terrain once again.

51.46 seconds – 0.44 quicker than her June best -  with Muhammed dethroned as Olympic champion but with a time of 51.58 that was astonishing in itself. Behind, Femke Bol of the Netherlands set a European record of 52.03 for bronze, now the fourth-fastest mark of all time.

Credit the track too, with the micro-pockets of air which its designers at Mondo proudly claims gives it “a trampoline effect”. Worth 1-2 per cent, some say. "It's one of those tracks that gives you that energy right back and pushes you forward," the victor said. Added Muhammad: "I can feel that energy return, especially when you go into (hurdle) eight and feel that death. I didn't feel like I was going into death."

World Athletics president Seb Coe defended the surface and the impact it – and the new range of super-shoes - has offered. “We do need to make sure we're not allowing designs or materials that really transform the sport into something we don't recognise,” he said. “I don't think we're there. At this moment I think we're in about the right place.”

Tech or not, McLaughlin believes there is more in her event to come. “I’ve never been happier to have retired,” joked Eilidh Doyle, eighth in the event in Rio.

"In terms of what's possible, I don't think there is such a thing as a true perfect race,” McLaughlin added. “We have such an amazing field of women and the more that we race each other, anything is possible. Technically there's always more to improve upon and I think in terms of what's possible, it's completely limitless."

After a silver and three bronzes, including in the 100m here, Canada’s Andre deGrasse finally acquired an Olympic gold in the 200m final, running 19.62 secs to hold off Kenny Bednarek with another American Noah Lyles third.

UK record holder Nick Miller threw a season’s best of 78.15m in the last round of the hammer but was sixth as Poland’s Wojciech Nowichi took a shock win.

Lizzie Bird ran a British record of 9:19.68 to come ninth in the 3000m steeplechase final with Uganda’s Peruth Chemutai taking gold in 9:01.45. While Emmanuel Korir and Ferguson Rotich claimed a Kenyan 1-2 in the men’s 800m.